1. Field of the Invention
The present invention relates to a tractor dolly assembly for use with a semi-tractor that is disabled that enables the tractor to be towed in a forward or reverse direction without the need to disconnect the drive shaft.
2. Description of the Prior Art
Various situations are known in which semi-trailers can not be transported in a normal fashion. For example, in situations in which the semi-trailer becomes structurally compromised due to a load shift or accident, semi-trailer dollies are known for supporting the trailer and enabling the semi-tractor to tow the disabled trailer to another location away from the location of the incident. An example of a semi-trailer tractor dolly assembly for use in such an application is disclosed in Lundin U.S. patent application Ser. No. 11/958,950, filed on Dec. 17, 2007,entitled Semi-Trailer Tractor dolly assembly, hereby incorporated by reference.
In yet other situations, the tractor itself becomes disabled either due to an accident or due to due to mechanical problems. In such a situation, the tractor is normally disconnected from the trailer and the trailer is transported to an alternate location by another tractor. The disabled tractor is then towed to an alternate location for repair by a tow truck Examples of devices for towing semi-tractors are disclosed in U.S. Pat. Nos. 4,555,214; 4,708,358; 4,861,221; 5,722,677; 5,845,920; 5,863,059; 6,120,051; 6,491,490; 7,017,934; and 7,100,933, all hereby incorporated by reference.
U.S. Pat. Nos. 4,555,214; 4,708,538; 5,722,677; 5,845,920; 5,863,059; 6,120,051; and 6,491,490 all disclose devices which are configured to be coupled to the fifth wheel assembly of the towing vehicle and the fifth wheel assembly of the towed vehicle As such, any available tractor with a fifth wheel assembly can be used as a tow vehicle, thus obviating the need for a dedicated tow truck, use of these devices requires the disabled tractors to be towed in reverse. Because the tractor is being towed in reverse, the drive shaft will rotate as the rear wheels of the towed tractor rotate during the tow. More particularly, either the drive shaft will have to be disconnected before the tow and reconnected after the tow, or the rear wheels will need to be lifted during the tow. Disconnecting and reconnecting the drive shaft is a rather cumbersome task. As such, the devices disclosed in U.S. Pat. Nos. 4,555,214; 4,708,358; 5,722,677; 5,845,920;5,863,059; 6,120,051; 6,491,490; 7,017,934; and 7,100,933 are all configured to tow the towed vehicle with the rear wheels lifted from the ground. Although the devices disclosed in the above mentioned patents are suitable for towing tractors with fifth wheel assemblies, those devices are generally unsuitable for towing large trucks which do not include fifth wheel assemblies, such as, dump trucks and other large trucks. In order to resolve this problem, U.S. Pat. No. 5,722,677discloses a towing device that can be coupled to a fifth wheel assembly on a tractor or alternatively coupled to the frame of a truck by way U-bolts.
The devices disclosed in the aforementioned patents all relate to mechanical devices that are not free standing devices As such, those devices must be manually lifted in place and connected to the two tractors. Such devices are thus relatively cumbersome to use.
U.S. Pat. Nos. 4,861,221; 7,017,934; and 7,100,933 all disclose free standing towing devices. In particular, U.S. Pat. Nos. 4,861,221 and 7,100,933 disclose wheeled devices that are adapted to be coupled to a fifth wheel assembly of tractor to be used as a towing vehicle. These devices include a hydraulically operated boom for lifting the front or rear of a vehicle. Based upon the configurations of these devices, they would only be suitable for lifting the front end of a semi tractor. As such, use of such a device to tow a semi tractor would require the drive shaft to be disconnected to avoid damage to the transmission.
U.S. Pat. No. 7,017,934 discloses a wheeled device for use in towing disabled semi tractors. In particular, the device disclosed in the '934 patent discloses a wheeled tractor dolly assembly for lifting the rear end of a semi tractor. A tow truck with a conventional tow bar is used to lift the front end of the tractor for towing. The wheeled tractor dolly assembly is coupled to the fifth wheel assembly of the disabled tractor and is therefore only suitable for use with semi tractors which have a fifth wheel assembly. Use of such a tractor dolly assembly only allows the tractor to be towed in a forward direction and is thus relatively limited in its application. Moreover, the tractor dolly assembly disclosed in the '934 patent is dependent on the configuration of the tractor, which vary. For example, some tractors have twin rear axles while others have a single rear axle. Also, the wheel base and location of the fifth wheel assembly is known to vary among tractors.
Thus, there is a need for a device for a device for use in towing large trucks including semi tractors which may not include a fifth wheel assembly that allows the large trucks to be towed in both a forward and reverse direction without the need to disconnect the drive shaft.